The in vitro diagnostics industry has been seeking technologies which afford the simultaneous discrete detection of multiple analytes. As an example, chlamydia and gonorrhea infections often are coincident in women. Collecting a specimen can be problematic so that a single assay which can detect both disease agents simultaneously is desirable. Another example is the current interest in Europe in the simultaneous detection of HIV-1 and HIV-2 antibodies in blood. Using present technology, a positive finding indicates the presence of antibodies to either one or both of the viruses but does not allow a determination of which antibody, specifically, is present. Such an assay technology has somewhat less diagnostic utility than a discrete assay affords but offers a measure of convenience and cost effectiveness.
Another reason for the interest in the simultaneous, discrete analysis of multiple analytes lies in the use of such technology in so called panel testing and screening assays. In panel testing, for a given specimens under diagnostic interrogation a number of different assays are always ordered together for the purpose of diagnostic interpretation. In screening assays, the laboratory always performs the same set of assays on every specimen in an effort to determine if the specimen is positive for one or more of the analytes in the screen.
An example of the latter application is screening of blood in the blood bank where every unit of donated blood is screened for HIV, HBV, HTLV, and HCV. In either of these situations a reagent technology which afforded the simultaneous discrete analysis of multiple analytes in a single reagent would have obvious cost and convenience benefits. Presently this need for efficient screens or panels is accommodated using robotics where multiple but separate assays are performed by a preprogrammed reagent and sample handling system. Such systems are expensive and can be unreliable.
It is therefore of interest to develop the capability to allow the medical diagnostician to perform multiple discrete simultaneous analyses of several analytes. It is also of interest to develop a low cost apparatus for carrying out multiple simultaneous analyses.